单选题 Identical twins are a perfect test case for theories of personality development. If a theory can't explain the differences between identical twins, then it cannot explain environmental effects on personality. Even identical twins brought up in the same home have different personalities.
Take Ladan and Laleh Bijani from Iran. They were identical twins who had spent their entire 29 years joined at the head. And yet, Ladan, the more outspoken of the pair, told journalists, "We are two completely separate individuals. We have different world views. We have different lifestyles. We think very differently about issues. " Why did Ladan and Laleh have different personalities?
Self-organized systems in insects can provide us with some ideas. A colony of ants, for example, can be seen as a self-organized systern. No supervisor tells the ants what to do, and yet all the jobs get done. The system works in such a way that if one ant carries out a particular job, it becomes less likely that another ant will attempt that job because it no longer needs doing. The result is what economists call "division of labor".
Self-organization also produces division of labor in human groups. Each individual looks for something to specialize in, his or her own suitable position in the group. If one position is occupied, the individual will seek another. This process increases the differences even between identical twins, because once they've chosen different specialties, a circular mechanism causes small initial differences between them to widen.
Although identical twins look very much alike, people who know them well will distinguish between them. They might, for example, address more questions and comments to one twin than the other — perhaps by chance first. But the consequence is that the twin who is addressed more often will do more talking than the other twin, which will cause people who know them to address still more of their questions and comments to that twin. The result, over time, will be one outspoken twin and one quieter one — like Ladan and Laleh Bijani.

单选题 According to the writer we learn that identical twins ______.

【正确答案】 A

【答案解析】细节题。对应的信息位于短文第一段最后一句：Even identical twins brought up in the same home have different personalities(即便是在同一个家庭中长大的同卵双胞胎也有着不同的个性)，选项[A]正是此句的改写，其中differ in sth.相当于be different in sth.或have different sth。其余三项都不对：[B]中的appearance(外貌)在文中没有提及，尽管最后一段中谈到了look very much alike(看上去很相像)，但短文主旨是双胞胎的性格而非外貌；[C]中的lifestyle见于第二段倒数第三句，但文中用的修饰词是different而非该选项中的same；[D]项中的outlook(观点，见解)也与第二段直接引语中的内容相反。

单选题 The ant colony is perceived to be self-organized because ______.

【正确答案】 B

【答案解析】推理判断题。由题干中的ant colony可迅速将研读重点定位到原文第三段。该段第二句指出：A colony of ants...can be seen as a self-organized system，接下来的两句进行了具体说明：No supervisor tells the ants what to do...because it no longer needs doing(没有管理者告诉蚂蚁们去做什么，但所有工作都有分工。如果一只蚂蚁做了某项具体工作，其他蚂蚁就不太可能再去做这项工作，因为不再需要去做它)。由此可以推知，蚂蚁是凭本能工作，并且每只蚂蚁所从事的工作都不一样，这正是[B]项的意思。其余各项都无法由原文合理推知：[A]项中的help others on a job(帮助别人做某项工作)、[C]项中的a particular group(某一蚁群)和[D]项中的a leading ant(领头的蚂蚁)和monitor(监控)都与原文意思不符。

单选题 It is said in the text that the working style of ants is characterized by ______.

【正确答案】 C

【答案解析】细节题。对应的信息位于原文第三段最后一句：The result is what economists call “division of labor”(这一结果就是经济学家们所称的“劳动分工”)，题目和选项[C]只是换了一种表达而已。事实上，其余三项在文中都没有提及：[A]项指“转换角色”，[B]项指“轮班工作”，[D]项指“集体努力”。

单选题 It can be inferred that the twins' differences have much to do with ______.

【正确答案】 D

【答案解析】推理判断题。本题较难，需要综合理解最后两段的意思才能选出正确答案。原文倒数第二段指出，“自我组织”这一机制使得人群之间进行劳动分工，每一个人都寻找自己的专长，寻找自己在群体中的适合位置，这一过程增加了双胞胎之间的差异。这显然属于双胞胎本身的、内在的影响因素。而在最后一段，作者又介绍了双胞胎周围的人如何区分双胞胎，这种区分方式强化了双胞胎间差异的形成，这明显属于不受双胞胎控制的、外部的影响因素。因此，作者实际上是强调了影响双胞胎性格差异的内、外两种因素，因此本题答案就是概括了这两方面的[D]项。其余三项都无法由原文合理推知。

单选题 The purpose of the text is to ______.

【正确答案】 C

【答案解析】主旨题。本题属于推断作者写作目的的主旨大意题。在短文中，作者以Ladan和Laleh Bijani这对连头同卯双胞胎为例，说明和分析了双胞胎性格差异的形成原因，没有驳斥和辩论，其目的只是为了将这一知识“告知”(inform)读者，因此本题答案就是[C]。其余三项中，[A]项entertain指“使娱乐，使感兴趣”，[B]项persuade指“说服”，[D]项argue指“争论，辩论”，它们明显都不对。